In recent years, significant advances have been made in the art of coin identification and validation, particularly with respect to electronic validators. The basic principles of coin identification and validation are well known. In the early days of coin operated vending machines, mechanical devices were used to attempt to identify and validate coins deposited into the machines. Some of the earliest machines simply accepted one denomination of coin and mechanical sizing apparatus was used to determine if the inserted piece was the proper size for that coin denomination. Naturally, such devices were susceptible to the use of slugs.
Later, mechanical devices based on fundamental kinematics were used to bounce deposited pieces off surfaces of predetermined resiliencies in order to validate coin mass. The normal discrepancy encountered between the mass of a slug of a given physical size and a coin would cause the coin to bounce through a path through which it could be tallied, and cause the slugs to bounce to a coin return path.
Beginning essentially with the invention of the transistor, electronic devices for validating coins started to be used. This trend continued, and expanded greatly as the circuit density of integrated circuits has increased through the 1970's and 1980's. In today's world, all electronic validators accepting multiple denominations of coins are in common use.
One of the older principles of electronic coin validation is determination of the metallic content of a coin piece by detecting its contribution to the inductance of an excited coil which is placed physically near the coin during its travel through the validator. Under these circumstances, the coin is acting as a metallic core to the coil and effects the overall terminal inductance seen at the terminals of the particular coil. Measuring a particular electronic parameter, such as the magnitude of an alternating current signal of a particular frequency determines the inductance of the coil/coin combination in a manner which gives information with respect to the metallic content of the coin.
Similarly, various electronic devices for determining coin diameter have been used, many of which employ sequentially masked and unmasked photodetectors.
An example of a modern all electronic validator is shown in U.S. Pat. No. 4,509,633 to Chow. The Chow apparatus employs sets of photodetectors having beams which cut across the coin path through the validator and appropriate timing circuitry to determine the diameter of a passing coin. An excited coil is used to detect the metallic content. Look-up table values for combinations of coil signal and diameter for a predefined set of valid coins are employed in order to accept or reject any coin piece inserted into the validator.
Another example of a coin discriminator or identifier is shown in U.K. patent application 2,135,905A to Leonard et al. The Leonard apparatus uses successively applied rectangular pulses to pairs of coils adjacent the coin path in order to determine both metallic content and diameter. The fundamental principle of the Leonard apparatus is to excite one of the coils in question which induces eddy currents in the coin. Once the excitation (a rectangular pulse) is removed, the decay of the eddy currents is measured. Additionally, the Leonard coin discriminator employs multiple coils of varying diameters. The eddy currents induced in the coils of differing diameters will produce different coil outputs as the eddy currents decay. In this manner, a sequence of critically timed rectangular excitation pulses applied to one coil, combined with measurement of the decay characteristics of the eddy currents as detected by another coil, is employed to use inductive coils to ascertain coin diameter as well as indications of metallic content. The approximately exponential decay rate of the current characteristic induced in the detector coil by the eddy currents is used to classify the coin. Again, look-up tables of known ranges of values for coins of specific denominations are employed to determine the validity and denomination of each piece passing through the system.
As is known to those skilled in the art, the primary purpose of coin discrimination apparatus and typical coin validators, used in an environment such as vending machines, is to determine the validity and denomination of the coin so that the total amount of money deposited at any given time may be calculated to see if the machine should vend its product or service. In most vending machine environments, all of the coins deposited are collected in a common collection box. It is well known that once the coin discrimination apparatus is operated, it is possible to use the output signals from the discriminator to physically sort coins into a plurality of receptacles, each of which is dedicated to receipt of coins of a particular denomination. Therefore, the coin discriminating apparatus of coin validators and sorters serve the common function of discriminating between valid and invalid coins, as well as determining the denomination of those determined to be valid.
The substantial technical problem encountered in making the transition from coin validation functions to coin sorting functions is the problem of throughput, or processing a sufficient number of coins per unit time to constitute an efficient sorting process. Coin validating apparatus, by its nature, tends to be serial in nature, thus it is normally designed in an environment where coins are processed one at a time.
Naturally, in the prior art there has been need to sort the heterogeneous collection of coin denominations which appear in the collection boxes of vending machines and other devices of the type described above. Usually, as the coins travel through the stream of commerce, they are packaged together in convenient collections of like denominations, such as the well known two dollar roll of nickels, five dollar roll of dimes, ten dollar roll of quarters, etc. used in the United States. These are distributed to business establishments to be used in making change. Much of the change finds its way to vending machines, toll collection points, and the like where, as described hereinabove, it is mixed in collection boxes with coins of various denominations.
Banking operations have a need to both count and sort large collections of coinage which arrives at various locations in a heterogeneous mixture of denominations. Other businesses, such as operation of pay telephones, parking meters, vending machines and others have large volumes of heterogeneous coin mixtures to handle.
Most prior art coin sorting devices are mechanical sizing machines. In other words, they assume the essential validity of the coins at the input and use varying mechanical devices to sort the coins by size and thus by denomination. One example of such a prior art machine are the well known shaker sorters which use trays perforated with holes of successively decreasing diameters. Coins will be provided over the shaker trays at an approximately predetermined rate per unit time and they are shaken as the coins travel down the path of the trays. The first set of perforations will be sized to pass the smallest diameter coin to block the passage of larger coins. A sufficient distance down stream from the first set of holes will be a second set of holes sized to pass the next diameter coin in the denomination set and used to block the others.
The flow in coins per unit time over the perforated trays and the number of perforations is empirically determined so that a very high percentage of the coins of each denomination will pass through the appropriate holes into collection bins dedicated to each denomination.
Additionally, rail sorters are well known to those skilled in the art in which a pair of diverging coin carriers are used such that the coins will drop when their underlying support gives away as a result of the spread of the rails as coins are passed over them. Also, coin sorters constructed with a spinning disk onto which the coins are dropped are known. On such devices, centrifugal force slings the coins out toward the outer periphery of the disk and various size exit channels are provided to sort the coins by size.
Once the coins have been sorted, there are several well known devices for repackaging them so that they once again appear in convenient rolls or other collections containing a predetermined number of coins. One example of such a coin packaging machine is shown in U.S. Pat. Nos. 3,707,244 and 3,751,871, to Hull et al. which are assigned to the assignee of the present invention. In this apparatus, a large number of coins of the same denomination are inserted into the interior of a rotating drum surrounded by a vacuum plenum. The drum is perforated with a plurality of counterbore locations into which the partial vacuum within the vacuum plenum sucks the coins as the drum is rotated. The counterbore locations rotate past inductive coin sensors which, when a coin is detected, activates an air jet to knock the coin into a coin chutes. In the Hull et al. patent, the output of the coin chutes includes apparatus for stacking the coins, ultimately for packaging in collections of predetermine numbers of coins of the same denomination. Additionally, the apparatus counts the number of coins detected and forced out of the counterbore locations into the stacking chutes. In this way, the total value of a large collection of coins of the same denomination can be ascertained as it is packaged.
A principal advantage of the coin packaging apparatus shown in the Hull '871 patents is its high throughput, i.e. the large number of coins per unit time that it can process and package.
It has come to the attention of the inventors of the present invention that it appears that a coin discrimination system described in the Leonard et al. U.K. application has been commercially exploited in the United Kingdom in a machine marketed under the name Titan 2408 Cash and Security Equipment Limited of Saint Albans in the U.K. It is not known to the inventors of the present invention whether this apparatus constitutes prior art to the present invention. The Titan coin sorting apparatus uses a rotating plate with a plurality of receptacles disposed about the periphery. It appears that coins are introduced toward the center of the rotating disk and move out to the edge and into the counterbores under the influence of centripetal force. They apparently pass over coin discriminating apparatus of the type described in the Leonard patent and some form of computing device keeps track of the denominations present at each location which are ultimately ejected when the coin is in registration with an appropriate output conduit for its denomination.
While little information is available to the inventors on the Titan 2408 machine, it has an apparent drawback that it processes coins only serially since the coins are only identified as they are carried in a receptacle along the outer periphery of the rotating disk. A technical specification for the machine which, on its face, is printed by the manufacturer, specifies 520 coins per minute as the throughput on the apparatus.
Since it seems apparent that the Titan 2408 uses a microprocessor or microcomputer in its operation, it will be apparent to those skilled that the cost of the electronics and denomination specific conduits are all provided for a single rotating disk in this machine. There is no apparent practical way to duplicate the number of disks in a practical embodiment of this type of machine in order to increase the throughput.
In this connection, it should be noted that the described sequence of excitation and detection in the Leonard U.K. patent shows a successive sequence of excitation pulses for which the timing is critical and which must be serially applied to each coin. Thus, it is conceivable, although the inventors do not know if this is the case, that the throughput of a machine such as the Titan 2408 is running at its maximum operating speed, given the signal generation and detection requirements of the Leonard coin identification scheme and the processing power of a typical high speed microprocessor.
Therefore, there is a need in the art for a dependable electronic coin sorting apparatus having a significantly higher throughput than that of a single disk machine such as the Titan 2408. Additionally, it is critical that such a machine be able to not only dependably sort, but to dependably count the amount of money sorted since many applications of such machines are on a service basis, i.e. the operator of the sorter is performing a sorting and counting service for the owner of the money. A typical example is the service of sorting coins from pay telephones. Given the significant throughput of a packaging apparatus such as that disclosed in U.S. Pat. No. 3,751,871 to Hull, it is desirable to use a structure and coin handling apparatus of the type disclosed in Hull '871 in a dependable coin sorting arrangement.
As noted hereinabove, the discriminator of the type shown in the Leonard U.K. patent requires multiple coils in order to identify coin size. The counterbores in the rotating interior drum of the coin packaging apparatus shown in the Hull patent must be sized so that they can accept the largest size coin of interest, normally a U.S. quarter, in the preferred embodiment. Under these circumstances, when smaller diameters coins are lodged in the counterbore, it was a rather trivial problem to detect the presence of some coin in one of the counterbores when the machine is fed with input consisting solely of coins of a single denomination. However, if a heterogeneous collection of coin denominations is fed into the Hull apparatus, the identification problem is exacerbated by the uncertainty of the particular portion of the counterbore which will be occupied by a given coin, such as a dime or a penny, of a smaller diameter than the diameter of the largest coin of interest.
It is extremely desirable in the art to be able to process a large number of coins through a coin discriminating apparatus in a manner which can detect a coin signature identifying its size and metallic content (and thus its denomination) using only electronic coils. Generally, this goal is achieved by the apparatus of the Leonard discriminator. However, the Leonard discriminator requires precise calibration and detection of small differences between similarly shaped exponential decay curves resulting from the eddy current decay described hereinabove in order to discriminate among coins. The apparatus of Leonard must provide a precision time base and detect slight differences on the order of microseconds in the exponential decay characteristics of the detected eddy currents. This leads to a relatively complex apparatus requiring precise components for establishing the time base and to more stringent calibration requirements. Additionally, the apparatus must rotate slowly enough such that a given coin covers the necessary sequence of coils for a sufficient period of time to allow the entire sequence of pulses described in the Leonard apparatus to be applied by the coin as it passes over the coils. Therefore, there is a need in the art for an all electronic coin sorter which can discriminate coins based solely on coil outputs, but which device employs a much simpler signature detection scheme that does not require the precise timing of pulses and detection of exponential decay characteristics.